Guidewire tip construction

ABSTRACT

Guidewire with an improved distal end. A guidewire with an improved distal end may include a core wire, a solder tip disposed at a distal end of the core wire, a radiopaque inner coil coupled to the distal end of the core wire, an outer coil disposed along the length of the core wire, and a distal hub coupled to the core wire and disposed proximate a distal end of the inner coil.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention pertains to guidewires for use withintravascular catheters. More particularly, the present inventionpertains to guidewires with an improved distal tip.

[0003] 2. Description of the Related Art

[0004] The use of intravascular catheters has become an effective methodfor treating many types of vascular disease. In general, anintravascular catheter is inserted into the vascular system of thepatient and navigated through the vasculature to a desired target site.Using this method, virtually any target site in the patient's vascularsystem may be accessed, including the coronary, cerebral, and peripheralvasculature. Examples of therapeutic purposes for intravascularcatheters include percutaneous transluminal angioplasty (PTA) andpercutaneous transluminal coronary angioplasty (PTCA).

[0005] Intravascular catheters are commonly used in conjunction with aguidewire. A guidewire may be advanced through the patient's vasculatureuntil it has reached a target location. Once in place, a catheter may bethreaded onto the guidewire and urged distally until the distal end ofthe catheter reaches a target location.

[0006] The vasculature of a human being can be a very tortuous path. Inorder for a guidewire to be steered through the vasculature, it may bebeneficial for the guidewire to be flexible, particularly near thedistal end. Increased flexibility may be incorporated into a guidewirein a number of differing ways. For example, the guidewire may bemanufactured from materials having a different flexibility, the distaltip may be tapered, etc.

[0007] In order to determine the location of the guidewire within thevasculature, a marker band may be coupled to the guidewire. The markerband may be fixedly attached to the distal tip of the guidewire so as toenable a clinician to accurately monitor the location of the guidewire.

BRIEF SUMMARY OF THE INVENTION

[0008] The present invention pertains to a refinement to guidewires.More particularly, the present invention pertains to a guidewire with animproved distal tip. Imaging the distal tip may allow the clinician toprecisely direct the guidewire to a specific location within thevasculature while monitoring its location on, for example, a fluoroscopyscreen.

[0009] The guidewire may comprise an elongate shaft having a proximalend and a distal end. A solder tip may be disposed at the distal end ofthe shaft. The radiopaque inner coil may be coupled to the distal end ofthe shaft proximate the solder tip. An outer coil may be disposed alongthe length of the shaft; a portion of the outer coil may be disposedover the inner coil. The distal end of the outer coil may be coupled tothe solder tip.

[0010] The inner coil may be disposed between a distal hub and aproximal hub. The distal hub may be coupled to the shaft and disposedproximate the solder tip. The distal hub may serve as a physical barrierbetween the solder tip and the inner coil. The proximal hub may becoupled to the shaft and disposed proximate the proximal end of theinner coil. The proximal hub may substantially prevent the inner coilfrom moving proximally along the shaft. The inclusion of the proximalhub and the distal hub may allow the distal tip to have a desired levelof flexibility in addition to a radiopaque coil that may be useful forimaging.

[0011] As an alternate to the inclusion of the proximal hub, the innercoil, the outer coil, or both may be coupled directly to the shaft. Forexample, the inner coil may be coupled to the shaft at a proximal end ofthe inner coil. Coupling the proximal end of the inner coil to the shaftmay allow the guidewire to comprise a desired level of flexibility.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0012]FIG. 1 is a cross-sectional view of an example distal tip of aguidewire;

[0013]FIG. 2 is a cross-sectional view of the distal end of anotherexample guidewire;

[0014]FIG. 3 is a cross-sectional view of the distal end of anotherexample guidewire;

[0015]FIG. 4 is a cross-sectional view of the distal end of anotherexample guidewire; and

[0016]FIG. 5 is a cross-sectional view of the distal end of anotherexample guidewire.

DETAILED DESCRIPTION OF THE INVENTION

[0017] The following description should be read with reference to thedrawings wherein like reference numerals indicate like elementsthroughout the several views. The detailed description and drawingsillustrate example embodiments of the claimed invention.

[0018]FIG. 1 is a cross-sectional view of the distal tip of a guidewire.A guidewire 10 comprises an elongate shaft or core wire 12 having aproximal end 14 and a distal end 16. An inner coil 18 may be disposed atdistal end 16 of core wire 12 and an outer coil 20 may be disposed alongthe length of core wire 12. A portion of outer coil 20 is disposed overinner coil 18. A tip 22 such as a solder tip, may be formed on core wire12 at distal end 16. A portion of outer coil 20 may be coupled to soldertip 22. A distal hub 24 is disposed proximate of solder tip 22.

[0019] Core wire 12 may be comprised of nickel-titanium alloy, stainlesssteel, a composite of nickel-titanium alloy and stainless steel.Alternatively, core wire 12 may be comprised of metals, polymers,combinations or composites thereof, or other suitable materials. Corewire 12, may be distally tapered. According to this embodiment, corewire 12 may include a plurality of distal segments or comprise a single,generally tapered distal end 16. Each distal segment may comprise adecreased outside diameter or individual segments may each taper alongthe length of a particular segment. A person of ordinary skill in theart could appreciate that a vast number of alternate configurations ofsegments and distal ends may be included without departing from thescope of the invention.

[0020] A portion of outer coil 20 may be embedded within solder tip 22.Embedded is understood to be disposed within, coupled to, set in,implanted, fixed, etc. Solder tip 22 may, thus, fix outer coil 20relative to core wire 12. Alternatively, outer coil 20 may be solderedto core wire 12 proximate solder tip 22.

[0021] Distal hub 24 is coupled to core wire 12 and may be disposedproximate solder tip 22. More particularly, distal hub 24 may bedisposed between solder tip 22 and inner coil 18. According to thisembodiment, distal hub 24 may serve as a physical barrier between soldertip 22 and inner coil 18. This physical barrier may prevent inner coil18 from becoming embedded within solder tip 22, particularly duringmanufacturing of guidewire 10 where molten or partially molten soldermay migrate along core wire 12. Distal hub 24 may be comprised ofpolytetrafluoroethylene (PTFE) or other suitable materials.

[0022] Inner coil 18 may be radiopaque. A radiopaque coil is understoodto be capable of producing a relatively bright image on a fluoroscopyscreen or another imaging technique during a medical procedure. Thisrelatively bright image aids the user of guidewire 10 in determining thelocation of distal end 16 of core wire 12. Radiopaque inner coil 18 maybe comprised of a number of radiopaque materials including, but notlimited to, gold, platinum, tungsten alloy, and plastic material loadedwith a radiopaque filler. Guidewire 10 may further comprise additionalradiopaque markers, for example near proximal end 14 of core wire 12. Itshould be understood that inner coil 18, alternatively, may comprise aplurality of individual coils that when taken together would have thesame general physical characteristics as inner coil 18.

[0023] In addition to distal hub 24, guidewire 10 may further comprise aproximal hub 26. Inner coil 18 may extend along core wire 12 betweendistal hub 24 and proximal hub 26. Inner coil 18 may be disposed betweendistal hub 24 and proximal hub 26 without being permanently fixed tocore wire 12 and be, thus, loosely disposed between distal hub 24 andproximal hub 26. Proximal hub 26 may also prevent inner coil 18 frommoving proximally relative to core wire 12. By disposing inner coil 18between distal hub 24 and proximal hub 26 without permanently fixinginner coil 18 to core wire 12, guidewire 10 may have increasedflexibility. Increased flexibility may enhance the ability of aclinician to advance guidewire 10 through the vasculature.

[0024] Alternatives to the embodiment shown in FIG. 1 may include innercoil 18 having a portion that coupled to core wire 12, outer coil 20,distal hub 24, proximal hub 26, or combinations thereof. Inner coil 18may be, for example, soldered to any one of the above elements at asingular location. According to these embodiments, inner coil 18 wouldbe fixed in a manner that would result in only a minimum change in theoverall flexibility of guidewire 10.

[0025] Proximal hub 26 may be comprised of polytetrafluoroethylene(PTFE). Alternatively, proximal hub 26 may be comprised of a heat shrinktube. In an exemplary embodiment, proximal hub 26 may be comprised ofmaterials similar to those listed above.

[0026] The dimensions of inner coil 18 may include a length of about,for example, 0.1 inches to 1.8 inches and the coil may define an outsidediameter of about, for example, 0.0080 inches to 0.0120 inches.According to an embodiment where inner coil 18 comprises a plurality ofcoils, spacing may occur between coils. The spacing may be a fixeddistance of about, for example, 0.3 inches to 0.8 inches or the spacingmay vary. The dimensions listed above are not intended to be limiting.Alterations to the dimensions of inner coil 18 may be incorporatedwithout departing from the scope of the present invention.

[0027] Outer coil 20 may extend proximally from solder tip 22 along thelength of core wire 12. Outer coil 20 may be brazed to proximal end 14of core wire 12. Outer coil 20 may be comprised of a nickel-titaniumalloy or stainless steel. Alternatively, outer coil 20 may be comprisedof materials similar to those listed above. In addition, outer coil 20may further comprise an outer silicone coating.

[0028] In at least some embodiments, it may be desirable to configureinner coil 18 and outer coil 20 so that they are wound or otherwisedisposed about shaft 12 in differing or opposite directions. Thisfeature is best seen and is described in accompanying description ofFIG. 4.

[0029] Guidewire 10 may further comprise additional features. Forexample, guidewire 10 may include one or more proximal marker bands.These marker bands may be disposed proximate proximal end 14 of corewire 12. In addition, a connector may be disposed at proximal end 14 ofcore wire 12 that may be used to couple an extension ribbon to guidewire10 (as shown in FIGS. 4 and 5).

[0030]FIG. 2 is a cross-sectional view of the distal end of an alternateguidewire. Guidewire 110 is essentially similar to guidewire 10 exceptthat inner coil 118 further comprises a proximal end 128 that may becoupled to core wire 12. The use of inner coil 118 may allow theomission of a proximal hub (i.e., proximal hub 26) as in guidewire 10.Alternatively, inner coil 118 may be used in conjunction with proximalhub 26.

[0031] Proximal end 128 may be coupled to core wire 12 by a number ofmethods. For example, proximal end 128 may be soldered to core wire 12.Alternatively, proximal end 28 may be heat bonded, coupled by a heatshrink tube, coupled by a polytetrafluoroethylene (PTFE), or othermethods that may comprise a physical joining of proximal end 128 ofinner coil 118 to core wire 12.

[0032] Coupling proximal end 128 to core wire 12, has a minimal impacton the flexibility of guidewire 110. Accordingly, proximal end 128 maybe soldered to core wire 12 at a single point so as to minimizepotential alterations in flexibility.

[0033]FIG. 3 is a cross-sectional view of the distal end of a secondalternate guidewire. Guidewire 210 is essentially similar to guidewire110 except that outer coil 220 further comprises a proximal region 230that may be coupled to core wire 12. In alternative embodiments, outercoil 220 may be used in conjunction with inner coil 18, with proximalhub 26, or any of the embodiments described herein.

[0034] Proximal region 230 may be coupled to core wire 12 by a number ofmethods including those described above. For example, proximal region230 may be soldered to core wire 12. Moreover, coupling of proximalregion 230 may be used independently of inner coil 118 being soldered(or otherwise coupled) to core wire 12.

[0035] Another example guidewire 310 is illustrated in FIG. 4. Guidewire310 is essentially the same in form and function as the other guidewiresdescribed herein, with a few exceptions as described below. Guidewire310 includes shaft 312 that includes distal end 316. Shaft 312 may becomprised of metals, metal alloys, polymers, combinations thereof, andthe like as described above in relation to shaft 12. For example, shaft312 may be comprised of nickel-titanium alloy. In at least someembodiments, shaft 312 has a narrowed or tapered region 332 proximatedistal end 316 similar to the tapered region shown in FIG. 1. Thereduction in the thickness of shaft 312 adjacent tapered region 332 may,for example, may aid in the maintenance of or otherwise improve thedistal flexibility of guidewire 310. Guidewire 310 may also include anyof the other structures or structural features described herein. Forexample, guidewire 310 may include a proximal hub similar to hub 24.

[0036] In at least some embodiments, shaft 312 may be truncated orotherwise terminate at a location proximal to distal solder tip 22. Adistal shaft or ribbon 334 may be coupled to distal end 316 of shaft 312and extend between shaft 312 and solder tip 22. Ribbon 334 may beincluded to serve a number of purposes. For example, ribbon 334 may becomprised of a thin strip of stainless steel and may provide someadditional structural support between the relatively rigid solder tip 22and the relatively flexible distal end 316 of shaft 312. Additionally,it may be desirable to improve the bonding of a nickel titanium alloystructure (e.g., shaft 312) with a tin or tin-indium based solderstructure (e.g., tip 22). According to this embodiment, ribbon 334 maybe use to enhance the bonding of shaft 312 and tip 22. For example,ribbon 334 may be comprised of stainless steel so that one end can beattached to solder tip 22 and the other end may be attached to distalend 316 of shaft (e.g., by adhesive, welding, soldering, crimping,banding, mechanical bonding, etc.).

[0037] Guidewire 310 may also include an inner coil 318 and an outercoil 320 that are essentially the same in form and function as coils 18and 20, respectively. For example, inner coil 318 may be comprised of,coated with, or otherwise include a radiopaque material and may bedisposed adjacent distal end 316 of shaft. Distal hub 24 may be disposedadjacent the distal end of inner coil 318 in a manner similar to what isdescribed above.

[0038] A number of couplings, connections, or attachments may joinvarious combinations of inner coil 318, outer coil 320, and shaft 312(and/or ribbon 334). For example, it may be desirable to attach outercoil 320 to inner coil 318. Alternatively, it may be desirable to joininner coil 318 to shaft 312, outer coil 320 to shaft 312, or to join allthree components. The type of attachment may also vary. For example, thevarious combinations of components may be joined by an adhesive, bysolder, by a weld, by a mechanical bond, or other suitable means.Moreover, the location of the connection may also be varied. Forexample, it may be desirable to join outer coil 320 and inner coil 318at a location adjacent proximal end 328 of inner coil. It can beappreciated, however, that it may also be desirable to join anycombination of the components adjacent proximal region 330 of outer coil320, adjacent the distal ends of inner and outer coils 318/320, or atessentially any other suitable position along the length of guidewire310.

[0039] In at least some embodiments, it may be desirable to alter thepitch of inner coil 318 and/or 320. For example, outer coil may includeone or more increased pitch regions 336 and inner coil 318 may includealso include one or more increased pitch regions 338. In embodimentswhere inner coil 318 and outer coil 320 are attached, it may bedesirable join coils 318/320 adjacent the increased pitch regions336/338. This arrangement may incorporate a number desirable featuresinto guidewire 310. For example, if a solder joint 339 is used to joincoils 318/320, including increased pitch regions 336/338 adjacent thejoint may help to reduce or prevent the spreading or wicking of solderlaterally from the joint. This feature is desirable because the wickingof solder may create stiff or generally less flexible regions ofguidewire 310 that may interfere with the desired flexibilitycharacteristics of guidewire 310.

[0040] Additionally, it may also be desirable to alter the direction ofthe winding of inner coil 318 and/or outer coil 320. For example, innercoil 318 may be wound in the opposite direction of outer coil 320. Thisfeature may incorporate a number of desirable features into guidewire310. For example, orienting the directions of the winding of coils318/320 may help to reduce or prevent any nesting that may occur betweencoils 318/320. Reducing or eliminating the nesting between coils 318/320may aid in the maintenance of the shape, profile, and integrity ofguidewire 310.

[0041] Another example guidewire 410 that is similar to other guidewiresdescribed herein is illustrated in FIG. 5. Guidewire 410 includes shaft412 that is essentially the same as shaft 312 and includes distal end416 and tapered region 432. Guidewire 410 also includes outer coil 420.In some embodiments, outer coil 420 may be comprised of a radiopaquematerial such as platinum or any of those listed above. Alternativelyouter coil 420 may be the same or similar to other outer coils describedabove.

[0042] Guidewire 410 may also include ribbon 434 that is essentially thesame as ribbon 334 that extends between shaft 412 and distal solder tip22. Ribbon 434 and shaft 412 may be attached similarly to what isdescribed above such as by adhesives or mechanical bonds. In addition toor as an alternative to the above attachment, ribbon 434 may be coupledto shaft 412 by a connector 440. Connector 440 may comprise a variety ofdifferent structures suitable for connecting ribbon 434 and shaft 412.For example, connector 440 may comprise stainless steel hypodermictubing. Alternatively, connector may be comprised of anickel-chromium-iron alloy such as INCONEL 625, which advantageouslywelds to both stainless steels and nickel-titanium alloys. INCONEL 625may be obtained from California Fine Wire Company of Grover Beach,California. It can be appreciated that connector 440 may be included inany other appropriate embodiments of the guidewires described hereinwithout departing from the spirit of the invention.

[0043] In at least some embodiments, a sleeve 442 may be disposed overat least a portion of shaft 412. For example, sleeve 442 may be disposedover the portion of tapered region 432 located proximally of outer coil420. According to this embodiment, sleeve may have a length in the rangeof about 10-45 centimeters (e.g., 30 centimeters) or longer. Sleeve 442may be attached to shaft 412 in essentially any suitable manner, forexample by an adhesive. Sleeve 442 may be comprised of a polymer such aspolyurethane or any other suitable material including those listedabove. Alternatively, sleeve 442 may be comprised of a polymer dopedwith radiopaque materials such as tungsten or tungsten alloys.

[0044] Similar to what is described above, a number of couplings,connections, or attachments may join any of the various combinations ofouter coil 420, shaft 412, ribbon 434, connector 440, and sleeve 442.Also, the type of attachment and the location of the connection orconnections may also be varied as described above. Additionally,guidewire 410 may also include other structural features described inrelation to other embodiments such as an inner coil similar to thosedescribed herein or a proximal hub such as hub 24.

[0045] Numerous advantages of the invention covered by this documenthave been set forth in the foregoing description. It will be understood,however, that this disclosure is, in many respects, only illustrative.Changes may be made in details, particularly in matters of shape, size,and arrangement of steps without exceeding the scope of the invention.The invention's scope is, of course, defined in the language in whichthe appended claims are expressed.

What is claimed is:
 1. A guidewire, comprising: an elongate shaft havinga proximal end and a distal end; a tip disposed at the distal end of theshaft; a radiopaque inner coil coupled to the distal end of the shaft,the inner coil having a proximal end and a distal end; an outer coildisposed along the length of the shaft, the outer coil having a proximalend and a distal end; and a distal hub coupled to the shaft and disposedproximate the distal end of the inner coil.
 2. The guidewire inaccordance with claim 1, wherein the shaft is comprised of stainlesssteel.
 3. The guidewire in accordance with claim 1, wherein the shaft iscomprised of nickel-titanium alloy.
 4. The guidewire in accordance withclaim 1, wherein the shaft is comprised of a composite ofnickel-titanium alloy and stainless steel.
 5. The guidewire inaccordance with claim 1, wherein the inner coil is comprised ofplatinum.
 6. The guidewire in accordance with claim 1, wherein the innercoil is comprised of gold.
 7. The guidewire in accordance with claim 1,wherein the inner coil is comprised of tungsten alloy.
 8. The guidewirein accordance with claim 1, wherein the outer coil is comprised ofstainless steel.
 9. The guidewire in accordance with claim 1, whereinthe outer coil is comprised of nickel-titanium alloy
 10. The guidewirein accordance with claim 1, wherein the distal end of the outer coil iscoupled to the tip.
 11. The guidewire in accordance with claim 1,wherein the proximal end of the inner coil is coupled to the shaft. 12.The guidewire in accordance with claim 1, wherein the outer coil furthercomprises a proximal section that is coupled to the shaft.
 13. Theguidewire in accordance with claim 1, wherein the distal hub iscomprised of polytetrafluoroethylene.
 14. The guidewire in accordancewith claim 1, further comprising a proximal hub coupled to the shaft.15. The guidewire in accordance with claim 14, wherein the proximal hubis comprised of polytetrafluoroethylene.
 16. The guidewire in accordancewith claim 14, wherein the proximal hub prevents the inner coil frommoving proximally relative to the shaft.
 17. The guidewire in accordancewith claim 1, further comprising a ribbon coupled to the shaft andextending between the shaft and the tip.
 18. The guidewire in accordancewith claim 17, further comprising a connector disposed adjacent ajoining portion of the shaft and the ribbon.
 19. The guidewire inaccordance with claim 1, wherein the outer coil is wound about the shaftin a first direction and the inner coil is wound about the shaft in asecond direction, and wherein the first direction is substantiallyopposite of the second direction.
 20. The guidewire in accordance withclaim 1, wherein the inner coil is coupled to the outer coil.
 21. Theguidewire in accordance with claim 20, wherein the outer coil includes afirst increased pitch region, and wherein the inner coil and the outercoil are coupled adjacent the first increased pitch region.
 22. Theguidewire in accordance with claim 21, wherein the inner coil includes asecond increased pitch region, and wherein the inner coil and the outercoil are coupled adjacent the second increased pitch region.
 23. Aguidewire, comprising: an elongate shaft having a proximal end and adistal end; a solder tip disposed at the distal end of the shaft; aradiopaque inner coil coupled to the distal end of the shaft, the innercoil having a proximal end and a distal end; an outer coil disposedalong the length of the shaft, the outer coil having a proximal end anda distal end; a distal hub coupled to the shaft and disposed proximatethe distal end of the inner coil; and a proximal hub coupled to theshaft and disposed proximate the proximal end of the inner coil.
 24. Theguidewire in accordance with claim 23, wherein the shaft is comprised ofstainless steel.
 25. The guidewire in accordance with claim 23, whereinthe shaft is comprised of nickel-titanium alloy.
 26. The guidewire inaccordance with claim 23, wherein the shaft is comprised of a compositeof nickel-titanium alloy and stainless steel.
 27. The guidewire inaccordance with claim 23, wherein the inner coil is comprised ofplatinum.
 28. The guidewire in accordance with claim 23, wherein theinner coil is comprised of gold.
 29. The guidewire in accordance withclaim 23, wherein the inner coil is comprised of tungsten alloy.
 30. Theguidewire in accordance with claim 23, wherein the outer coil iscomprised of stainless steel.
 31. The guidewire in accordance with claim23, wherein the outer coil is comprised of nickel-titanium alloy. 32.The guidewire in accordance with claim 23, wherein the distal end of theouter coil is coupled to the solder tip.
 33. The guidewire in accordancewith claim 23, wherein the proximal end of the inner coil is coupled tothe shaft.
 34. The guidewire in accordance with claim 23, wherein theouter coil further comprises a proximal section that is coupled to theshaft.
 35. The guidewire in accordance with claim 23, wherein the distalhub is comprised of polytetrafluoroethylene.
 36. The guidewire inaccordance with claim 23, wherein the proximal hub is comprised ofpolytetrafluoroethylene.
 37. The guidewire in accordance with claim 36,wherein the proximal hub prevents the inner coil from moving proximallyrelative to the shaft.
 38. The guidewire in accordance with claim 23,wherein the outer coil is wound about the shaft in a first direction andthe inner coil is wound about the shaft in a second direction, andwherein the first direction is substantially opposite of the seconddirection.
 39. The guidewire in accordance with claim 23, wherein theinner coil is coupled to the outer coil.
 40. The guidewire in accordancewith claim 39, wherein the outer coil includes a first increased pitchregion, and wherein the inner coil and the outer coil are coupledadjacent the first increased pitch region.
 41. The guidewire inaccordance with claim 41, wherein the inner coil includes a secondincreased pitch region, and wherein the inner coil and the outer coilare coupled adjacent the second increased pitch region.